locks, driver's won't lock, passenger stuck locked no motor

Post Wed Sep 02, 2009 2:14 am

ok Willnz and Brian, here is what I found:
Keep in mind that the "unlock" at the doors in not working. I can unlock the individual door with the key, but I cannot unlock the passenger from the driver's and cannot unlock the driver's from the passenger.

If I earth pin 7 and 8 at the central lock unit- the doors lock.
If I earth pin 9 at the central lock unit - the doors unlock.
If I earth pin 6 at the central lock unit - nothing happens.

I checked and do have continuity between the green/blue wire at the driver's door and pin 6 on the central lock unit.
I have continuity between the passenger door green/blue and pin 6 at central lock unit.
I have continuity between the driver's and passenger's door green/blue wires.
I also checked for path to earth at each of the green/blue wires in the doors and then check out ok.

So, what do you think the issue is? Thanks

Post Wed Sep 02, 2009 2:43 am

Thanks man. I guess you work nights? I have to keep the time difference in mind and I did not think anyone would respond tonight. In 5 hours I will have crashed for the night, but I will check back in the morning. Thanks!!!!

Post Thu Sep 03, 2009 2:51 pm

ok, new findings. When I jumper 6 and 9 the locking unit unlocks the doors. The problem is that I did not put them to earth. As soon as my jumper wire, which is wedged in pin 9, touches pin 6, I get action. I did not even have to then put an additional wire to earth.
In my previous post, I did check for continuity and a path to earth and on the green blue wire of pin 6 and they checked out ok. So, what does this mean. Is there some sort of internal fault in the C/L box?

Post Thu Sep 03, 2009 10:24 pm

This is heading towards the suggestion I made a couple of pages ago that you need to connect the locking ECU via a spare socket, so that you can only connect the red/black, brown, blue, white and black wires. That would allow you to determine exactly what's happening.
I've never actually connected pins 6 and 9 together on a locking ECU ( I found out the hard way some time ago, Willnz, that 6 and 9 aren't physically linked as the wiring diagram suggests! ), but I would expect absolutely nothing to happen. What you are finding suggests that one of the pins is permanently earthed, either by a fault in the ECU, or the wiring connected to it.

Post Thu Sep 03, 2009 11:23 pm

That was good timing, i've been having the same trouble with mine the last few days and resorted to pulling it apart yesterday.
All i managed to achieve was finding out that the ECU when reconnected will work for exactly two goes and then pack up.

It still works from the boot lock but the drivers door would only lock once and then unlock once and then stop working. (deadlock still works from drivers door)
It would do exacly the same with a spare ecu and even the original as long as i unplugged it and then plugged it back in

Reading through the bits i have it explains that the ECU has a thermal cut out to stop it overloading the motors, so in theory it should stop working for a while if the CL has been activated too many times.

Does anyone know what the vertical piece on the corner is ?
I'm hoping its a prehistoric polyfuse of some kind but i've never seen one like it.
The way the ECU works means it has to work with the current flowing in either direction. (if it is the thermal cut out)

Post Fri Sep 04, 2009 1:15 am

Thing in the corner is a "one shot" thermal fuse. It's operation couldn't be simpler - if the current passing through the resistor gets too high, it gets hot enough to melt the special low melting point solder holding the small leaf spring to the top of it. The spring jumps back, and the circuit is permanently broken.
The ECU also does seem to have a self resetting "fuse" as you describe as well, which stops the unit working for a short while if excessive demands are made of it, but I've never seen a mention of it in print, and since I have yet to trace out the complete circuit of one, I've no idea where and how it works.

Post Fri Sep 04, 2009 2:52 am

Brian, can you explain again what you would want me to do with the extra plug. I have one. But, do I really need to splice into my existing harness? How would you do that anyway? Use wire taps that you just crimp together? I checked to see if the door unlock wire had continuity to earth and it did not. Thanks

Post Fri Sep 04, 2009 5:20 am

Ok, so I essentially am putting the spare plug in between the original plug and the C/L unit. I then only connect red/black, brown, blue, white and black wires? I do not connect the four unlock/lock wires? What do I do then? Sorry, I don't quite understand the process. Thanks for helping me sort this out.

Post Sun Sep 06, 2009 9:33 pm

ok, I am in the process of splicing a spare connector together. But, I did find out that if I unplug both door actuators and then touch pin 6 to 9, I do not get any unlock action, without touching to earth. But, as soon as I plug either one of the actuators in, if i touch pin 9 to 6, I get unlock action, even without touching to earth. So, nothing happens when I have the actuators unplugged. It as if the permanent earth between 6 and 9 disappears. What does this suggest? I will continue to set up my spare plug to further diagnose. Thanks.

Post Sun Sep 06, 2009 10:25 pm

OK, I made the connector and put it in between the the original plug and the C/L unit. I connected all the wires except for:
yellow blue door lock
green purple boot unlock
green black boot lock
green blue door unlock

They all worked beautifully EXCEPT the green blue door unlock. That is still dead in the water. So, does this mean the wiring is ok and the box is crap? Thanks guys.

Post Sun Sep 06, 2009 10:31 pm

clydesdale wrote: So, does this mean the wiring is ok and the box is crap? Thanks guys.

If what you report is accurate, it confirms the ECU is faulty, but that in no way confirms the wiring is OK! You'd be a bit unlucky if it was faulty as well though.

Post Sun Sep 06, 2009 10:43 pm

Thanks Brian. So, now what? Can I open it and is there something to fix, or is it time to find a new used one? I think a new new one would be pricey. Thanks.

Post Sun Sep 06, 2009 10:52 pm

You've got a one off fault here, so I can't comment on whether its fixable. There's none of these nasty surface mount components in it so you possibly stand a chance, if you can fault find at component level in electronic circuits.
A new one is expensive, but a second hand one will suffice, although ideally you should open it up and check for signs of water damage, and for signs of bodging around the thermal fuse.

Post Mon Sep 07, 2009 12:04 am

I read through the rest of the stuff i have and at the bottom of a diagram in very small print it had the helpful warning.
"DO NOT UNPLUG THE LOCKING ECU WITH THE BATTERY CONNECTED OR YOU WILL DAMAGE THE UNIT"
I'll be looking for a new one then

OEM quotes them at about 90 euros

Transistors from maplins at 60p a go are looking very tempting.

Post Mon Sep 07, 2009 12:23 am

Martinaston wrote: "DO NOT UNPLUG THE LOCKING ECU WITH THE BATTERY CONNECTED OR YOU WILL DAMAGE THE UNIT"

I wouldn't take too much notice of that!

Post Sat Sep 12, 2009 2:27 am

I just read about the battery, too late, but no damage. I plugged my new ebay locking unit in and it works like a charm. Thanks for your tremendous diagnostic help. I ended up putting in a new lock with my tumblers and used central locking unit. Thanks gents.